Vibration damping suspension



Feb. 45, 1945. H. .J. SEIDEL. ETAL v VIBRATION DAMPING SUSPENSION FiledOct. 10, 1940 Fig.1

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Patented Feb. 6, 1945 VIBRATION DAMPING SUSPENSION I Hans JoachimSeidel, Berlin-Wilmersdorf, and Adolf Weiler, Berlin-Spandau, Germany;vested in the Alien Property Custodian Application October 10, 1940,Serial No. 360,688 In Germany October 18, 1939 5 Claims. (01. 248-5) Theinvention relates to a suspension of power plants or of similarinstallations producing-vibrations, particularly aircraft power plantsby means of sleeve type springs, preferably with rubber asresilientmaterial, The sleeve type rubber springs embrace a carrier bolt in sucha manner that a direct connection between bolt and rubber sleeve is notnecessary. 1

Suspensions of this kind are already known per se. Withthese'ararngements the sleeve type rubber springs are connected with theengine installation serving for mounting the power plant into the celland provision is made on the casing of the power plant to receive themounting bolts. This mode of suspension has the disadvantage, that it ismechanically unfavourable for connecting the mounting bolts with thecasing parts which are preferably made of light metal or correspondingalloys, for in such cases the points of application of the mountingbolts at the casing must be strengthened for a 'more favourabletransmission of power in order to avoid a'break age of the bolt and/or adamage to the casing. Further, different manufacturing works design thecells to correspond to certain engine installa- These disadvantages areavoided, according to the invention, by the fact that the rubber springsform a part of the power plant. A particularly simple construction isprovided by applying the sleeve type springs in a preferablycirculargroove provided in the engine. crankcase or in an essential partof it. v

This circular groove is closed by a closing device like a cover. In thisclosing device apertures are provided through which the mounting bolt,being articularly or rigidly connectedwith the carrier bolt, projects.In this manner the sleeve type springs forming constituent parts of thecrankcase and thus of thepower plant'can be designed from the first insuch a way that no resonance vibrations of the power plant occur withinthe range of operating speed of. rotation of engine and propeller.

Preferably the sleeve type springs are not equally spaced in thecircular groove, but arranged, according'to the desired elasticity ofthe engine installation with respect to the wing of the aircraft, inrelation to the vertical and the transversal axes so that naturalfrequencies of both the said axes possibly coincide; In'this manner thedifferences in the elasticity of the engine installation can almost becompensated in these directions of axes. This distribution of the sleevetypesprings can be adapted subsequently to the actual engineinstallation or predetermined already from the first. Further owing tothe insertion of the complete sleeve type spring into the crankcase themechanical structure of the suspension becomes considerably morefavourable, as now the forces are transmitted from the crankcase anddistributed over the large surface of the sleeve so that any localoverstressing of the crankcase no longer occurs. Since at the same timethe sleeve springs have become con-' stituent parts of the engine, it ispossible to I mount the same power plant in different cells T Thestructural details of the sleeve type springs mounted in theapproximately circular recess and fitted. tobe closed by a cover may beseen from the following description. The drawing shows the inventionwith its essential parts in two examples of construction, in which Fig.1 isa side view of the suspension partly in section;

Fig. 2 is a circular arrangement of a sleeve type spring in section;

Fig. 3 is a view of another form of circular arrangement of the sleevetype spring with the cover plate removed, partly in section.

' riphery with a groove 4' which is semi-circular in cross-section (Fig.4) and co-operates with the known per se and as shown in Fig. 2 a sleeveHi The.

and a carrier bolt II to' which a resilient material, preferably rubber,is bonded. The mounting bolt 1 is specially put on the carrier bolt IIor forms one piece with it. The mounting bolt 1 projects through arecess I3 of the sleeve II), as can be seen in Figs. 4 and 5..

In order to mount such sleeve type springs in the circular groove3 ofthe bell-shaped part 2 of the crankcase, the carrier bolt I I is, as tobe seen in Fig. 2, curved in conformity with the curvature of thecircular groove 3 and providedat its ends preferably with cylindricalextensions: I4.

The surface of the sleeve I is shaped toconform to the curvature andcircular cross-section 4 of the channel formed by the grooves 3 and 4'and split for the introduction of the carrier bolt I I which in theexample of construction ismacle' ly'the same spring volume and that.further the ratio of the characteristics of resiliency in transof onepiece with the mounting bolt 1, the division plane running in thedirection of the axis of the mounting bolt. In this manner it ispossible' to insert-the mounting bolt 1 together with the carrier LboltII into the divided sleeve and tosecure the rubber cover I2 byvulcanizing, so that all .The bore at the ends of the sleeve I0 and theextensions I4 serve 'for screwing in or for in- :serti'ng specialabutments in the shape of rings the I5. The inner width of these ringsis large enough that during normal operating conditions the car,-

rier bolt II with its extensions -I4- is nowhere abutting. With rowingstresses, 1.. e., through staticistresses due to the influence ofexternal forces, :e. g., propeller traction, torque or during levellingup the airplane, the extensions-I4- of the carrier bolt I I abut againstthe annular stops I5. In this way forces, e. g., below 1.5 resp. 2.5, g.are transmitted, without interfering with the rubber cover, directly tothe suspensionpoints, :so that the rubber is dealt with sparingly. Ifsuch limiting stops would be lacking, therewouldbe 5 the danger of therubber cover becoming destroyed or at least slackenedi from itsassembly.

Instead of adapting the entire-surface of the sleeve III to the shapeof-the recess 3,:it is also possible, as shown .byv the example ofconstruction in Fig. 3, to provide the sleeve with a rectilinearcylindrical bore and, e. g., to turn down the middle part of the sleeveon its outer surface at I I, so that the sleeve is not abutting thegroove '3. Into the bore I6 of the sleeve the carrier bolt I I togetherwith the mounting bolt I is inserted and the spring elements I2 are puton to both ends of the carrier bolt II and fixed byscrewing.upthenutsIIL- A H .1

'Between the'mounting. bolt I and each spring element I2 an abutment I9.is :provided -..0n:the .bolt III. Both these abutments I9 can abut on I,the' interior wall of .thesleeve I0 andhave the same object as theannular abutments I 5 of the example of construction inFig, 2'. ;-Thearrangement of :these abutments inithe immediate vicnity of the mountingbolt I has the advanta'gethat the bending movements, in the caseof theabutments on the 'carrierbolt II becoming efiective,

willremain smallin-amount. V H

' 6, of the cover plate 4.

The spring elements I2 are in this example of construction independentstructural parts and are inserted into the inner bore I6 of the sleeveI0 against the ends, respectively, of a spacing ring provided in thebore I6. The spring elements I2 are held in the sleeve I0 preferably byannular screw members 2I screwed into the sleeve III, and, according tothe position of these two screw members 2I, the spring elements can beso adjusted or displaced that the mounting bolt 1 occupies apredetermined position in the recess The subdivision of the resilientmaterial in two independent spring elements has the advantage that thecharacteristics of resiliency can be kept lower with approximateversedirection to that in longitudinal direction becomes smaller. This isessential for the purposeof obtaining low natural frequencies.

In the form of the device illustrated in Fi 3,

the sleeve I0 is provided at each end'with an enlarged portion 22 havingits outer 'surface 23 suitably shaped toconform to both the curvatureand cross-sectional configuration of the groove 3 so that the portions22 have their, entire outer surfaces 23 in contact with the Wall of thegroove 3. In the form of Fig. 3, the axes of the sleeves IIIand thebolts II coincide andare tangent to a circle concentric with the; groove3 and passing through the center-of its cross-section. The sleeves Itmay be fixed in the groove .3 by bolts 24 engaging. in recesses 25 inthe portion 22.

While -there is illustrated in the drawinga r groove 3 which iscircular, it is to be understood that the groove 3 may be onlyipartiallycircular,

and in such a groove the sleeve type'sprin'gs -5 could be mounted; i IThe circular form, however, has the advantage, that the sleeve typesprings 5 can be arranged in the groove 3 at will. There is further thepos sibility of fastening the cover plate '4' by means of the mountingbolts 24 simultaneously securing the position of the I sleeve typesprings 5. We claim: I

l. In a vibration-damping suspension, the

- combination of a 'supporting structure "a suspended structure, one ofsaid structures .being provided with a. groove; a plurality ofsuspension members interposed between said structures,-each of. saidmembers comprising a sleeve, a bolt dis posed within said sleeve, andresilient means interposed between said sleeve and said bolt, the sleevebeing received in said groove in the one 'structureg means to retain thesleeves in'the groove;--and a carrier bolt connecting the bolt of eachof the suspension members and the other 7 of said structures.

2. In a vibration-damping suspensiomthe combination of a supportingstructure; a'suspended structure provided with a circular groove,semicircular in cross 'section; a pluralityof suspension members, eachcomprising a sleeve, a resilient member'mounted in said sleeve,-andabolt mounted .-in said resilient "member, the sleeve having an outersurface conforming to the curvatureand cross-section of-said groove,andbeing disposedtherein; means to retain thesleeves-in the groove; anda carrier bolt connecting the bolt of each. suspension member andthesupporting structure. I

3. In a vibration-dampingsuspension, thecornbination of a supportingstructurepa suspended structure having a circumferential channel; v.a

plurality ffi s s on' m mbe s. ea h comprisin toretain the sleeves inthe channel; and connecting means between the bolt of each member andthe supporting structure.

4. In a vibration-damping suspension, the combination of a supportingstructure; a suspended structure provided with a circular groove,semicircular in cross-section; a cover member removably attached to saidsuspended structure and having a plurality of apertures communicat-' ingwith said channel, and a circular groove, semi-circular incross-section, the grooves being so designed and related, when the coveris attached, as to form a circular channel, circular in cross-section;a'plurality of suspension members mounted in said channel, each of saidsuspension members having a sleeve having an exterior configurationconforming to the curvature of said channel, a resilient member mountedin said sleeve, and a bolt mounted in said resilient member; and acarrier bolt connected to the bolt of each suspension member, passingthrough one of said apertures, and connected with said supportingstructure.

5. In a vibration-damping suspension, thecombination of a supportingstructure; a suspended structure provided with a circumferential groove,semi-circular in cross-section; a cover plate removably attached to saidsuspended structure and having a plurality of apertures and a circumferential groove, semi-circular in cross-section,

the grooves being so designed and related when the cover is attachedthat they co-operate to form a circumferential channel, circular incrosssection; a plurality of suspension members mounted in said channel,each member comprising a sleeve having a rectilinear bore, and anexterior enlarged portion on each' end, each of said portions being soformed that its entire surface contacts the walls of said channel, whenthe,

member is mounted in the channel, a rectilinear boltin the bore of saidsleeve, the longitudinal, axes ofthe bore and the bolt co-inciding andbeing tangent to the circle concentric with the circumferential channeland passing through the center of the circular cross-section of thechannel, and a pair of rubber collarsslidably mounted on said bolt andbearing on said sleeve; and a carrier bolt connected'with the bolt ofeach suspensionmember, passing through one ofxsaid apertures andconnected with the supporting structure.

HANS JOACHIM SEIDEL. ADOLF WEILER.

